New ATLAS publication

Measurement of the tttt production cross section in pp collisions at sqrt(s)=13 TeV with the ATLAS detector” has been submitted to JHEP. Members of the IFAE-ATLAS team (Aurelio Juste, Nicola Orlando, and Anil Sonay) have played a leading role in this publication, from designing the analysis strategy to the final multivariate technique and statistical analysis employed.

This paper presents a measurement of the four-top-quark production cross section in final states with a single lepton or an opposite-sign lepton pair in association with multiple jets using the full Run 2 dataset collected with the ATLAS detector. With four top quarks produced per event, this is a very rare Standard Model process with a predicted cross section of only 12 fb, and thus is very sensitive to beyond-the-SM (BSM) contributions. A sophisticated event categorization and multivariate technique is used to discriminate signal from background events. The result of this analysis is combined with a previous measurement in multilepton final states. The combined cross section is measured to be a factor of two higher than the SM prediction, although compatible with it within 2.0 standard deviations. The corresponding observed (expected) signal significance is .7 (2.6) standard deviations over the background-only prediction.

The IFAE team is currently working on an improved analysis targeting BSM production of four-top-quark events. Stay tuned!

More information on the ATLAS Physics Briefing


Latest Group News


IFAE at EPS-HEP 2021

July 27, 2021

The European Physical Society conference on high energy physics 2021 (EPS-HEP 2021), one of the most important conferences in HEP of the year, is taking place online this week. Three IFAE groups are participating:

ATLAS Milestone

ATLAS celebrates results of 1000 collision papers

June 30, 2021

The ATLAS Collaboration celebrates the creativity, wealth and scientific impact enshrined in its 1000 papers using LHC collision data.


Phenomenology 2021 Symposium

May 26, 2021

Anil Sonay, member of the IFAE-ATLAS group at gave the talk “The search for rare top production and decay processes with the ATLAS experiment at the LHC” at Pheno 2021 on 24-26 May 2021